seatbelt buzzer wiring Options

[JeffBowlsby]

QUOTE

Where do the yellow wire go to

In my best Obi-wan voice...

Jim...the diagram....use the diagram....

Check you starter solenoid again, there should be a big yella wire going to it.

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

[r_towle]

this diagram from Bowlsby should be in the classic thread...

Rich

[double-a]

QUOTE (ejm @ Nov 10 2005, 11:18 PM)

This pic shows how the factory bridged the starter wiring when they eliminated the starter interupt relay in favor of the warning light/buzzer only.

looks like they just hooked them end to end with one of those rectangular plastic thingies that appear in other places on the car. maybe i'll go that route. or maybe i'll leave the scotch clip and hope for the best (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

~a

[jim_hoyland]

I've been wondering how the relay worked. My only reference is how a standard power relay works: small current triggers a larger current. There are a lot of wires at passenger seat relay ie Bowslby's diagram. How do the seat belt wires, in-seat wires, and other work together ???

Really curious,

[r_towle]

I was just informed that it may be that these have ground triggers verus positive triggers...

That explains all the ground wires...

It is clearly a multi function relay...for both seat pressure and seat belt connection..

Im bringing it to my EE Dad tommorow for a detailed anaylsis....cause I wanna know too....

Rich

[jim_hoyland]

Now we're getting somewhere ! Really looking forward to getting the details

[MecGen]

You Guys (IMG:http://www.914world.com/bbs2/html/emoticons/aktion035.gif)

Keep us informed on what you find. Great info here.
Might be a good place for a car alarm.

Salut
(IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[jim_hoyland]

Exactly ! When we know how that thing works, there are prolly some new or unintended uses that it could help with.

[r_towle]

ok..,.,.

I have delivered a complete wired up relay...wiring digrams etc...so...we should know by this weekend WHYit works and HOW is works...

Rich

[grasshopper]

well??? (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Carlitos Way]

I'm not sure where I read this.. or if it is accurate... but wasn't there a recall to have dealers bypass this "feature" in the past?

[grasshopper]

QUOTE (Carlitos Way @ Nov 27 2005, 02:50 PM)

I'm not sure where I read this.. or if it is accurate... but wasn't there a recall to have dealers bypass this "feature" in the past?

yes (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[r_towle]

This is from DAD,

Only partly (80%). I did spend several hours on it. Lots of diagrams but no analysis yet. I will get back to it but I can't promise when.
Within the module is a printed circuit board with several resistors, diodes, and transistors along with two relays. The other module is a relay (buzzer probably). I have reverse engineered most of the circuits but not enough yet to come to any conclusions. One problem is the relays are so badly corroded that I cannot trace the circuits tied to them. The rest of the circuits are clearly all the logic associated with the buzzer and warning light. I have traced most of them but ran out of time. If anyone has another module less corroded it would help. Also if there is any diagram of the leads coming to the module it would be very helpful in analyzing the insides of the module. All I have is the earlier 1973 version without a module.
One puzzle , not yet solved, is how many leads coming to the module are hot (12v). One possibility is the heavy leads you bypassed are the only source of 12v and only when the ignition is turned on.
Another possibility comes from the 1973 schematic which shows some black leads coming from fuse 11 which are hot all the time and could be trouble if shorted to ground. I am not sure when I can get back to it so if I were you I would just terminate them with some protection to prevent grounding.
One question I have is "Do you know of any time when the buzzer and/or light is supposed to come on without the ignition being on....such as key left in lock (off) and door opened?

[r_towle]

Im gonna need some help here.

Does anyone have a seatbelt relay that they dont want and yet is not all rusty...

And/or...does anyone have a detailed wiring diagram for the 74 seat belt buzzer system...possibly out of the true porsche service manual???

Rich

[jim_hoyland]

Glad to see this is still a work in progress. Very interested in learning more here; anuy one got a donar ?

[Dave_Darling]

The wiring diagram is available here:

http://www.pelicanparts.com/914/914_electr...al_diagrams.htm

The Dreaded Seatbelt Interlock Relay is on Page 4 of the 74 diagram, and is component J34.

The only power-in on the relay is on the following terminals:
15 (black wire) constant power.
L (yellow/red wire) switched power--after it goes through the warning light.
C (yellow wire) power when the key is in "start" only.
H (grey/yellow wire) switched power, which runs the "door ajar" buzzer.

...Come to think of it, I believe that "L" isn't actually an input, but an output for the light. When the relay grounds L, the light comes on.

I have a relay somewhere in my Stash Of Parts ™, but it'll take a long time for me to find it...

Basically, the relay does nothing at all but turn on the light and interrupt the signal going to the starter. The only wires going to it that are in any way important are the ones where two wires are crimped into one metal connector. If you want to take the socket out completely, then splice together any pair of wires that are crimped into the same metal connector. That will leave all the functionality of the car intact, except for the door-ajar buzzer, the seatbelt warning light, and the starter interrupt.

--DD

[Mikey914]

Ok, I'm missing the relay, so rather than waste my money buying another, I can connect The heavy yellows together, and then connect all double clipped wires together. Then secure remaining wiresou to of the way, correct? (IMG:http://www.914world.com/bbs2/html/emoticons/dead horse.gif)

[Rleog]

This may be a dumb question, but I really don't know: Where do the yellow wire go to. They are huge, I assume they are related to the start function. I don't recall seeing a yellow wire at the starter or solonoid. The pictures are great, hope to clean this mess up.

I found this thread very useful while reconditioning my wiring harness, which is out of the car. As Dave suggested, you can use the wiring diagram to answer Jim's question.

More easily for future users:

The Yellow/Red stripe wire originates on the Regulator Plate (Relay Board) within the 14 pin connector at terminal #1 then runs to the seat belt "Logik-Relais" (Bosch's nomenclature) The solid Yellow wire runs from the seat belt Logik-Relais to the steering column switch.

Thanks to all who contributed to this thread.

[Dave_Darling]

That's true for the 74 cars, and some 75s. The "Logik-Relais" is the Dreaded Seatbelt Interlock Relay, which was added in 74 as a DOT-mandated safety measure and then removed in 75 as a DOT-mandated safety measure. In earlier and later cars, the yellow wire runs from the ignition switch to the relay board without being interrupted by the relay.

The relay is a failure point; it is common to remove it and splice the two thick yellow wires together to bypass its function.

--DD

[r_towle]

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